In liquid crystal display devices, print heads or the like, conventionally, electronic parts, such as a chip of a semiconductor integrated circuit, are connected with a wiring pattern by the so-called face down bonding wherein electrodes projecting from the electronic parts are directly connected with the wiring pattern of a circuit board without using leads.
In the electronic part assembly, a whole surface of a circuit board is covered with synthetic resin such as epoxy resin after assembling the electronic parts so that the electronic parts will not fall off after assembling. However, in the electronic part assembly, a great number of electronic parts are closely arranged. Accordingly, if one of the electronic parts is to be replaced with alternatives, the synthetic resin fixing the integrated circuits need to be fused by heating. As a result, the other integrated circuits, which do not need to be removed, would be undesirably affected by heat.
In order to solve such a problem associated with the prior art, an electronic part assembly of a semiconductor device has previously been proposed and such a device is disclosed in Japanese Unexamined Patent Publication No. 241847/1991. The assembly comprises, as shown in FIG. 9, an integrated circuit 11 mounted on a circuit board 7, a projecting electrode 12 formed under an electrode pad 11a of the integrated circuit 11 and pressed against a wiring pattern 6 formed on the circuit board 7 to come in contact therewith, a cover member 13 covering the integrated circuit 11 and bonded at its leg 13a to the circuit board 11, and a rubber member 14 disposed between an internal face 13b of the cover member 13 and a reverse side surface 11b of the integrated circuit 11 so as to press the integrated circuit 11 downward and thereby to maintain electrical contact between the projecting electrode 12 and the wiring pattern 6. The assembly thus arranged allows the integrated circuit 11 to be readily replaced with its alternative without substantially affecting other integrated circuits. This is because the integrated circuit 11 can be removed only by fusing adhesive bonding the leg 13a to the circuit board 7.
With such a structure, however, the rubber member 14 is likely to deteriorate if the structure is used under an environment of a high-temperature of for example, more than 85.degree. C. and a high-humidity of, for example, more than 85%, the resilience of the rubber member 14 decreases. This leads to a decrease in the pressing force of the rubber member 14 against the integrated circuit 11. Accordingly, there arises a problem of a continuity failure between the projecting electrode 12 and the wiring pattern 6. Further, there is such a problem that a cover member is bonded to the rubber member by pressing it by a force more than a compression force of the rubber member when the semiconductor device is assembled.